Macular degeneration results from the malfunctioning or loss of function of photo-sensitive cells in the retina. According to the Macular Degeneration Foundation, more than 13 million people in the United States are affected; a new case of adult macular degeneration is diagnosed in the U.S. every three minutes. A study in the August 2001 issue of the Archives of Ophthalmology found that a higher intake of specific types of fat, including vegetable, monounsaturated and polyunsaturated fats, may be associated with a greater risk for advanced adult macular degeneration. Foods with higher levels of these fats overall tend to be highly processed, store-bought snack foods. Conversely, diets high in omega-3 fatty acids, which are primarily found in certain types of fish such as albacore tuna and salmon, seem to lessen the risk. Johanna M. Seddon, director of epidemiology at the Massachusetts Eye and Ear Infirmary and an associate professor at Harvard Medical School and Harvard School of Public Health, was lead author of the study. The multi-center study took place at the Massachusetts Eye and Ear Infirmary, Manhattan Eye, Ear and Throat Hospital in New York, the Wilmer Eye Institute in Maryland, and the University of Illinois at Chicago.